Treatment of products made with cellulose derivatives



Patented Jan. 1%, TQZB.

UNITED STATES PATENT CQDFFTQE.

LAWRENCE GEORGE RICHARDSON, OF WEST BRIDGEFORD, NEAR NOTTINGHAIMI,ENC-:-

LAND, ASSIGNOR T0 AMERICAN CELLULOSE AND CHEMICAL MANUFACTURING COMPANYLIMITED, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

TREATMENT OF PRODUCTS MADE WITH 'CELLULOSE DERIVATIVES.

N 0 Drawing.

To all whom it'may concern:

Be it known that. I, LAWRENCE Gnome RICHARDSON, a subject of the King ofGreat Britain and Ireland, of Vest Bridgeford. near Nottingham, England,formerly of Spondon, near Derby, England, have invented certain new anduseful Improvements Relating to the Treatment of Products made withCellulose Derivatives, of which the following is a specification.

In the process of preparing or dyeing of threads. filaments or fabricsof cellulose acetate. described in British Specification No. 11886 of1920, and specification of United States application Serial No. 461978.the cellulose acetate is subjected to a partial and limited degree ofsaponification before or during dyeing.

In those specificationsthe use. of sodium hydroxide was moreparticularly described as a matter of economy and convenience, it beingunderstood that any other saponifyiug agents having a similar effect maybe employed.

In carrying out the process orginallydescribed, it was foundadvantageous not to discharge the exhausted saponification bath afterthe treatment of the silk, but to use it again, repeatedly, after theaddition each time of the requisite fresh amount of sodium hydroxidesolution, so that sodium acetate accumulated in the bath, and couldultimately be recovered.

It has been found that such accumulation or presence of sodium acetatein the bath is of advantage not only from an economical point of Viewbut also from a technical standpoint. as, amongst other facts, itspresence in the bath intensifies or controls the partial saponificationand enables level dyeing to be more easily obtained on the goods.

According to the invention we add sodium acetate to the baths in whichthe partial saponification of cellulose acetate threads, filaments orfabrics, and in particular of cellulose acetates lower than triacetate.is to be effected or it may be added to dyebaths when the partialsaponification and dyeing are conducted as a single operation indyebaths which permit of the presence of sodium acetate.

The effect is not bound to any particular concentration of sodiumacetate as it is obtained with Very small amounts, e. g. soluApplication filed August 31, 1921. Serial No. 497,380.

tions of about 1% or With larger amounts or with relatively highconcentrations. The best effects are however found to be obtained withlow concentrations of sodium acetate. The action of small quantities ofsodium acetate in the bath is probably a chemical one.

By way of example we may make up a fresh saponifying bath containing anyconvenient quantity of sodium acetate, for in stance about 1 to 2%, sayabout 10 to 20 lb. per 100 gallons, (though we do not confine ourselvesto this amount as we may use more or less) and in this bath we mayveffect the partial saponification of 10 lb. of cellulose acetate silkafter the addition of 0.25 to 0.5 lb. of sodium hydroxide at atemperature of about 50 to 75 C. until the sodium hy droxide isexhausted or approximately so. The exhausted bath may be repeatedly madeup again with fresh quantities of sodium hydroxide and used again forthe treatment of fresh quantities of silk as before mentioned if sodesired.

We do not bind ourselves to any definite concentration of added sodiumacetate. nor

to any exact quantity of the sodium hydroxide or other saponifyingagent. nor to the particular temperature indicated. for the partialsaponification, but we state that the addition of quantities of sodiumacetate, preferably in small quantities, intensities the reaction andfavours the obtainment of level dyeing as mentioned above.

What I claim and desire to secure by Letters Patent is 1. The hereindescribed method of facilitating the: dyeing of threads, filaments orfabrics of or containingcellulose acetate, and in particular ofcellulose acetates lower than triacetate, which comprises subjecting thesame to limited alkaline saponfication in an aqueous bath containingsodium acetate.

2. The herein described method of facilitating the dyeing of threads.filaments or fabrics of or containing cellulose acetate. and inparticular of cellulose acetates lower than triacetate, which comprisessubjecting the same to limited alkaline saponification in an aqueousbath containing a small quantity of sodium acetate.

3. The herein described method of facilitating the dyeing of threads.filaments or fabrics of or containing cellulose acetate,

and in particular of cellulose acetates lower than triacetate, whichcomprises subjecting the same to limited alkaline'saponification in anaqueous bath containing about 1 to 2 per cent of sodium acetate.

4-. The herein described method of facilitating the dyeing of celluloseacetate, and in particular of cellulose acetates lower than thiacetate,which comprises subjecting the same to alkaline saponification in anaqueous bath containing sodium acetate and a quantity of alkalinesaponit'ying agent sufiicient only to effect partial saponifica-tion ofthe 'cellulose acetate, until the saponifying agent is practicallyexhausted.

The herein described method of facilitating the dyeing ofcelluloseacetate, and in particular of cellulose acetates lower thantriacetate, which comprises subjecting the same to alkaline saponifi-ation in. an aqueous-bath containing sodium acetate and a quantity ofcaustic soda sutficient only to effect partial saponification of thecellulose acetate, until the caustic soda is practically exhausted.

(5. The herein described method of facilitating the dyeing of celluloseacetate. and in particular of cellulose acetates lower than triacetate,which comprises subjecting the same to alkaline saponification in anaqueous bath at about 75 0., containing sodium acetate and a quantity ofalkaline saponifying agent sufl icient only to effect partialsaponification of the cellulose acetate. until the saponifying agent ispractically exhausted.

7. The herein described method of facilitating the dyeing of celluloseacetate, and in particular of cellulose acetates lower than triacetate,which comprises subjecting the same to alkaline saponification in anaqueous bath, containing about per cent sodium acetate and a-quantity ofalkaline saponifying agent suflici ent only to effect partialsaponification of the cellulose acetate, until the saponifying agent ispractically exhausted.

8. The herein described method of facilitating the dyeing of celluloseacetate, and in particular of cellulose acetates lower than triacetate,which comprises subjecting the same to alkaline saponification in anaqueous bath containing about a per cent sodium acetate and a quantityof caustic soda sufficient only to effect partial saponification of thecellulose acetate, until the caustic soda is practically exhausted.

9. The'herein described method of facilitating the dyeing of celluloseacetate, and in particular of cellulose acetates lower than triacetate,which comprises subjecting the same to alkaline saponification in anaqueous bath at about 5045" 0., containing about 5 per cent sodiumacetate and a quantity of alkaline saponifying agent sufficient only toeffect partial saponification of the cellulose acetate, until thesaponifying agent is p 'actically exhausted.

10. The herein described method of facilitating the dyeing of threads,filaments or fabrics of or containing cellulose acetate,

and in particular of cellulose acetates lower than triacetate, whichcomprises subjecting the same to limited alkaline saponification in anaqueous dye bath containing sodium acetate.

11, The herein described method of facilitating the dyeing ofthreztdsfilaments or fabrics of or containing cellulose acetate. and inparticular of cellulose acetates lower than triacetate which comprisessubjecting the same to limited alkaline saponification in an "aqueousdye bath containing a small quantity of sodium acetate.

12. The herein described method of fa-cilitating the dyeing of threads,filaments or fabrics of or containing cellulose acetate and inparticular of cellulose acetates lower than triacetate, which comprisessubjecting the same to limited alkaline saponification in an aqueous dyebath containing about 1 to 2 per cent of sodium acetate.

Tn testimony whereof I have hereunto subscribed my name.

LAWRENCE GEORGE RICHARDSON.

